Compounds that selectively eliminate tumor cells with an aberrant genotype may provide a greater therapeutic index and allow for genotype-based patient selection. After screening >1 million compounds for those with oncogenic-RAS-selective-lethality, we have identified four oncogenic-Ras-selective lethal scaffolds (RSL scaffolds) that we named erastin, RSL3, ML162 and SRS7-31. We have elucidated key aspects of their mechanism of action, including: (1) these compounds are more potent in tumor cells with constitutive activation of the RAS-RAF- MEK pathway, (2) they cause a form of iron-dependent oxidative cell death that is morphologically, genetically and biochemically distinct from apoptosis, necrosis, autophagic cell death and necroptosis, which we have termed ferroptosis, and (3) they ultimately cause tumor- selective lipid peroxidation, resulting in membrane damage and non-apoptotic cell death. Here, we seek to test and extend our hypothesis that tumors harboring activated RAS-RAF- MEK signaling are sensitized to ferroptosis. This hypothesis will be evaluated in vitro and in vivo, as these compounds are validated, to move testing of this mechanism and these compounds towards a clinical setting. The significance of the proposed research is that it will result in validation of a set of lead compounds and associated mechanisms that allow for selective targeting of tumor cells harboring oncogenic mutations in Ras pathway genes, especially pancreatic cancers, almost all of which have activating KRAS mutations.